Automatic speech recognition (ASR) allows a computing device to understand human speech. Automatic speech recognition (ASR) can use language models for determining plausible word sequences for a given language using the result of an audio processing by an acoustic model as input. Understanding human speech enables voice-to-text transcription and voice commands, among other functions. In real world situations, speech need to be understood in a variety of acoustic environments. It is a challenge for a single acoustic model to accurately identify sounds across a plurality of environments and speakers.